As integrated circuits (ICs or chips) become increasingly smaller and faster, electrical signals used in various types of ICs are also subject to increasing delays caused by capacitance, inductance, or resistance in the ICs. At a certain high speed and/or frequency, such delays become a design concern. To avoid potential signal delay issues, optical signals are used instead of electrical signals for data transmission in some situations. Such an approach leads to a combination of a chip for handling electrical signals and another chip for handling optical signals in an IC package.